Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 132138

Area Forecast Discussion
National Weather Service Houston/Galveston TX
338 PM CST Sat Jan 13 2018


...Today through Tuesday Night...
Quiet and cool weather this weekend will gradually warm to the
upper 50s to mid 60s by Monday as high pressure slides east and
onshore flow returns. Low temperatures tonight are forecast to dip
below freezing across most of the inland areas, but a hard freeze
is not anticipated.

Rain chances increase Monday evening through Tuesday as a cold
front pushes through the area. The predominant precipitation type
is expected to be rain, however there is still a slight chance of
some wintry precipitation mixing in across the northern parts of
the area early Tuesday morning. At this point it`s still a little
to early to nail down precipitation type, and for now all types
of frozen precipitation (snow, sleet, and freezing rain) are on
the table. It really comes down to how fast the cold air sweeps in
behind the front vs how quickly the post-frontal precip ends. The
ECMWF is faster with the front bringing it through more overnight
Monday night, vs the GFS/NAM solutions of a Tuesday morning
frontal passage. Previous ECMWF run showed faster drying behind
the front in addition to being quicker than the others, however,
the latest run is showing some lingering precipitation well after
the freezing line passes. Although confidence is slowly increasing
that frozen precipitation is possible, overall chances are still
fairly low. Right now, the best chance for frozen precipitation is
along and north of a Columbus-Conroe-Livingston line. If frozen
precip falls, light accumulations (<0.1 inch) will be possible.
With temperatures falling throughout the day Tuesday and into
Tuesday night, any wet surfaces remaining will likely freeze with
low temperatures in the low 20s to low 30s Tuesday night. A Hard
Freeze Warning may be required for portions of the area. 11

...Wednesday through Saturday...
High pressure builds in Wednesday behind the cold front and will
quickly progress eastward across the Central Plains. Onshore flow
and moisture will return Thursday as the surface high moves over
the Tennessee Valley. An upper-level shortwave trough moves
through the area Thursday night with strong warm air advection and
lift, so precipitation is expected Thursday night through Friday.
The biggest issue is if the precipitation begins early enough on
Thursday to catch the below freezing temperatures, freezing rain
is possible along the northernmost counties. Confidence is
currently low enough that no fzra was included in the grids, but
it is something we will watch out for moving forward. Behind the
shortwave, a gradual warming trend will continue through the
weekend before the next cold front passes on Sunday. 22


Will be keeping the Low-Water Advisory up through the evening hours
given the combination of moderate NE flow and low astronomical tide
times helping to keep MLLW levels at/around -1 foot. Elevated winds
and seas have also persisted over the offshore waters and will also
maintain the SCEC for these locations into this evening.

As high pressure continues to move off to the east...we will be see-
ing a slow veering of winds to the east overnight through tomorrow.
Generally light SE winds are expected across the coastal waters Sun
night and should persist through Mon. Models remain on track with a
strong cold front moving into the Gulf Tues afternoon. Gusty north/
northeasterly winds in the wake of the boundary will likely require
Small Craft Advisories Tues night into Weds morning. The associated
arctic high building down from the Plains is forecast to linger in/
around the Middle MS Valley region through the rest of the week and
its proximity should keep moderate/strong east winds in place. 41


College Station (CLL)      48  30  53  35  61 /   0   0   0   0  10
Houston (IAH)              48  32  53  37  62 /   0   0   0   0  10
Galveston (GLS)            47  41  48  46  57 /   0   0   0   0  10


GM...Low Water Advisory until 10 PM CST this evening for the
     following zones: Galveston Bay...Matagorda Bay.

     for the following zones: Waters from Freeport to the
     Matagorda Ship Channel from 20 to 60 NM...Waters from High
     Island to Freeport from 20 to 60 NM.



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